The Olmsted County Program Project was initiated in 1966 to pursue a variety of epidemiologic studies by exploiting the potential of the medical records linkage system of the Mayo clinic. Since its inception this record linkage system has been expanded, through cooperation with other local and regional facilities, to include reference to virtually all of the medical records for Olmsted County residents for the last 40 years. This resource has made possible the completion of nearly 100 epidemiologic studies (with 40 more in progress) as a result of collaboration among the investigators of the core facility, Mayo clinicians and pathologists, investigators from outside institutions and students. The studies have ranged from descriptive incidence, prevalence, and trends (as in meningitis, multiple sclerosis and myeloma), to etiologic studies of prognosis in relation to risk factors (as in ischemic heart disease), and have included projects which clarified the role of heredity (as in hypospadias). We propose to continue and broaden this series by including new descriptive studies on such topics as ischemic and rheumatic heart disease, peripheral vascular disease, hypertension and diabetes and of these conditions as precursors of stroke; investigations of the relationships of therapeutic irradiation, rectal polyps, and benign breast lesions to subsequent malignancies are also planned or under way. We propose to improve the organization of the file and increase the amount of substantive content which is retrievable by computer to facilitate a variety of family-based studies including mental retardation, congenital malformations and malignancies, and possible long-term effects of specific drugs such as diethylstilbestrol and anticonvulsants. We propose to do a pilot study to explore the benefits to be derived by supplementation of the current file with data obtained through a health interview and examination survey in a sample of Olmsted County residents. The facility will continue to encourage and support research training for graduate students and undergraduate medical students.